1. Field of the Invention
The present invention relates generally to a wireless charger, and more particularly, to a wireless charger and a charging control method therefor, which can supply an optimal induced electromotive force according to where a charging target is placed on the wireless charger.
2. Description of the Related Art
Generally, for operation of a mobile terminal, a power should be continuously supplied. To this end, the mobile terminal includes a battery which is generally charged by a charger. In a charging method, research on non-contact charging methods and wireless charging methods have been conducted to support mobility of the mobile terminal.
In the wireless charging method, the location of a coil in a mobile terminal which is a target to be charged (hereinafter, “charging target”), and the location of a coil in a charger which charges the mobile terminal are important factors in determining charging efficiency. To improve charging efficiency, techniques for arranging coils of a charging target and a wireless charger are presently being studied.
FIGS. 1A and 1B illustrate examples of a general wireless charging method. As illustrated in FIGS. 1A and 1B, a currently used wireless charging method includes an arrangement charging type and a multicoil charging type.
In the arrangement charging type, a user directly arranges a charging target 10 on a wireless charger 20 of a cradle type or arranges the location of the charging target 10 by using a magnetic force employing a magnet included in the wireless charger 20. In the multicoil charging type, a plurality of coils are arranged in a wireless charger 30 and coils corresponding to the location of a charging target are selected for charging from among the plurality of coils.
In this way, the conventional wireless charging method uses the arrangement between coils. However, since the arrangement is performed by a user using his/her hands or by using a magnet, it may be inconvenient for a user and charging efficiency may be decreased due to an inaccurate arrangement. In the multicoil charging type, since many coils are used, charging efficiency is lowered, costs are increased, and it is difficult to control individual coils. Accordingly, a method is needed which can supply an optimal induced electromotive force according to the location of a charging target in a wireless charger in consideration of convenience for users.